Generally, a digital rights management (DRM) is technique to protect a rights object (RO) for digital contents and systematically manage it, and provides a protecting and managing scheme for preventing an illegal copy of the contents, obtaining the RO, generating/moving the contents, and consuming the RO and the contents.
FIG. 1 is a configuration view showing a DRM system in accordance with the related art.
As shown, the DRM system controls contents issued to a user by a contents provider to be consumed only in a right-limit of RO. The contents provider is an entity corresponding to a Contents Issuer (CI) and/or a Rights Issuer (RI).
The CI issues contents protected by a specific encryption method (hereinafter, will be referred to as DRM contents) so as to protect contents from a user having no access right, and the RI issues a Rights Object (RO) necessary to consume the DRM contents.
A DRM agent is mounted at a device thus to receive the DRM contents and RO from the CI or the RI, and controls a consumption of the DRM contents at a corresponding device by analyzing a ‘License’ contained in the RO. The License consists of a ‘Permission’ and a ‘Constraint’.
In the related art DRM system, the RI has managed a certain domain. That is, the RI was able to add or delete a specific device to/from the certain domain. In the domain management method of the related art, as only one RO is issued to a certain domain, all devices in the certain domain can use the RO by copying and installing the RO each other. Therefore, the related art allows all devices in the certain domain to use evenly the RO.
However, since the related art has not defined any procedure corresponding to a case where an RO issued to a specific device is sent (moved or transferred) to second and third devices, a user's request for keeping on using the RO by sending the RO to any device although the specific device leaves a domain has not been appropriately treated and utilities of the DRM system and digital contents have been degraded accordingly.